// Copyright 2021 Liuxiangchao iwind.liu@gmail.com. All rights reserved.

package nodes

import (
	"bytes"
	"context"
	"encoding/json"
	"fmt"
	"github.com/TeaOSLab/EdgeCommon/pkg/configutils"
	"github.com/TeaOSLab/EdgeCommon/pkg/dnsconfigs"
	"github.com/TeaOSLab/EdgeCommon/pkg/rpc/pb"
	"github.com/TeaOSLab/EdgeCommon/pkg/serverconfigs"
	"github.com/TeaOSLab/EdgeDNS/internal/accesslogs"
	"github.com/TeaOSLab/EdgeDNS/internal/configs"
	teaconst "github.com/TeaOSLab/EdgeDNS/internal/const"
	"github.com/TeaOSLab/EdgeDNS/internal/events"
	"github.com/TeaOSLab/EdgeDNS/internal/remotelogs"
	"github.com/TeaOSLab/EdgeDNS/internal/rpc"
	"github.com/TeaOSLab/EdgeDNS/internal/utils"
	"sort"
	"time"
)

var sharedNodeConfigManager = NewNodeConfigManager()

type NodeConfigManager struct {
	notifyChan chan bool
	ticker     *time.Ticker
	timezone   string

	lastConfigJSON []byte

	lastAPINodeVersion int64
	lastAPINodeAddrs   []string // 以前的API节点地址
}

func NewNodeConfigManager() *NodeConfigManager {
	return &NodeConfigManager{
		notifyChan: make(chan bool, 2),
		ticker:     time.NewTicker(3 * time.Minute),
	}
}

func (this *NodeConfigManager) Start() {
	for {
		select {
		case <-this.ticker.C:
		case <-this.notifyChan:
		}
		err := this.Loop()
		if err != nil {
			if rpc.IsConnError(err) {
				remotelogs.Debug("NODE_CONFIG_MANAGER", err.Error())
			} else {
				remotelogs.Error("NODE_CONFIG_MANAGER", err.Error())
			}
		}
	}
}

func (this *NodeConfigManager) Loop() error {
	client, err := rpc.SharedRPC()
	if err != nil {
		return err
	}
	resp, err := client.NSNodeRPC.FindCurrentNSNodeConfig(client.Context(), &pb.FindCurrentNSNodeConfigRequest{})
	if err != nil {
		return err
	}
	var configJSON = resp.NsNodeJSON
	if len(configJSON) == 0 {
		return nil
	}

	// 检查是否有变化
	if bytes.Equal(this.lastConfigJSON, configJSON) {
		return nil
	}
	this.lastConfigJSON = configJSON

	var config = &dnsconfigs.NSNodeConfig{}
	err = json.Unmarshal(configJSON, config)
	if err != nil {
		return err
	}
	err = config.Init(context.TODO())
	if err != nil {
		return err
	}
	sharedNodeConfig.Store(config)
	configs.SharedNodeConfig.Store(config)

	this.reload(config)

	events.Notify(events.EventReload)

	return nil
}

func (this *NodeConfigManager) NotifyChange() {
	select {
	case this.notifyChan <- true:
	default:

	}
}

// 刷新配置
func (this *NodeConfigManager) reload(config *dnsconfigs.NSNodeConfig) {
	teaconst.IsPlus = config.IsPlus

	accesslogs.SharedDNSFileWriter().SetDirByPolicyPath(config.AccessLogFilePath)
	accesslogs.SharedDNSFileWriter().SetRotateConfig(config.AccessLogRotate)

	needWriteFile := config.AccessLogWriteTargets == nil || config.AccessLogWriteTargets.File || config.AccessLogWriteTargets.ClickHouse
	if needWriteFile {
		_ = accesslogs.SharedDNSFileWriter().EnsureInit()
	} else {
		_ = accesslogs.SharedDNSFileWriter().Close()
	}

	// timezone
	var timeZone = config.TimeZone
	if len(timeZone) == 0 {
		timeZone = "Asia/Shanghai"
	}

	if this.timezone != timeZone {
		location, err := time.LoadLocation(timeZone)
		if err != nil {
			remotelogs.Error("TIMEZONE", "change time zone failed: "+err.Error())
			return
		}

		remotelogs.Println("TIMEZONE", "change time zone to '"+timeZone+"'")
		time.Local = location
		this.timezone = timeZone
	}

	// API Node地址，这里不限制是否为空，因为在为空时仍然要有对应的处理
	this.changeAPINodeAddrs(config.APINodeAddrs)
}

// 检查API节点地址
func (this *NodeConfigManager) changeAPINodeAddrs(apiNodeAddrs []*serverconfigs.NetworkAddressConfig) {
	var addrs = []string{}
	for _, addr := range apiNodeAddrs {
		err := addr.Init()
		if err != nil {
			remotelogs.Error("NODE", "changeAPINodeAddrs: validate api node address '"+configutils.QuoteIP(addr.Host)+":"+addr.PortRange+"' failed: "+err.Error())
		} else {
			addrs = append(addrs, addr.FullAddresses()...)
		}
	}
	sort.Strings(addrs)

	if utils.EqualStrings(this.lastAPINodeAddrs, addrs) {
		return
	}

	this.lastAPINodeAddrs = addrs

	config, err := configs.LoadAPIConfig()
	if err != nil {
		remotelogs.Error("NODE", "changeAPINodeAddrs: "+err.Error())
		return
	}
	if config == nil {
		return
	}
	var oldEndpoints = config.RPCEndpoints

	rpcClient, err := rpc.SharedRPC()
	if err != nil {
		return
	}
	if len(addrs) > 0 {
		this.lastAPINodeVersion++
		var v = this.lastAPINodeVersion

		// 异步检测，防止阻塞
		go func(v int64) {
			defer func() {
				if r := recover(); r != nil {
					remotelogs.Error("NODE", fmt.Sprintf("goroutine panic: %v", r))
				}
			}()

			// 测试新的API节点地址
			if rpcClient.TestEndpoints(addrs) {
				config.RPCEndpoints = addrs
			} else {
				config.RPCEndpoints = oldEndpoints
				this.lastAPINodeAddrs = nil // 恢复为空，以便于下次更新重试
			}

			// 检查测试中间有无新的变更
			if v != this.lastAPINodeVersion {
				return
			}

			err = rpcClient.UpdateConfig(config)
			if err != nil {
				remotelogs.Error("NODE", "changeAPINodeAddrs: update rpc config failed: "+err.Error())
			}
		}(v)
		return
	}

	err = rpcClient.UpdateConfig(config)
	if err != nil {
		remotelogs.Error("NODE", "changeAPINodeAddrs: update rpc config failed: "+err.Error())
	}
}